Apparatus for polishing plates of glass, marble, or other material



Oct. 15, 1928. 1,687,959 v F. B. WALDRON v APPARATUS FOR POIlISI-IING PLATES OF GLASS, MARBLE, OR OTHER MATERIAL Filed Sept. 5,. 1924 Patented Oct. 16, 1928.

UNITED STATES- PATENT- OFF-ICE.

IREDERIC BARNES WALDROII, OF PBESCOT, ENGLAND, ASSIGNOB TO PILIIIGTOI BROTHERS LIMITED, OF LIVERPOOL, ENGLAND, A BRITISH COIPANY.

APPARATUS FOR POLISHING PLATES OI GLASS, MARBLE, OR OTHER. HATER-ILL.

Application filed September 5, 1924, Serial No, 735,985, and in Great Britain September $8,138.

This invention relates to apparatus for polishing plates of glass, marble or other material, and more particularly to that type of polishing apparatus in which a plurality 5 of polishing blocks, each adapted to rotate about its own axis, are mounted on a framework which rotates about its axis, and said invention has for its object an improved construction of polishing runner whereby t0 the polishing blocks, in normal operation,

rotate about their own axes without the need of any means for driving them positively.

According to this invention each polishing block is mounted loosely on its stub splndle, so that it is free to rest evenly on the surface of the glass by its own weight, and the contact between the stub spindl and the block, whereby the" latter 1s he d against Centrifugal force, is in a plane which passes approximately through the centre of gravity 1 of the block or between the centre of gravity and the operativeface of the block.

This invention, will be described as applied 25, to the runner commonly employed for polishmeans of a nut 7. The boss 6 fits loosely in a cylindrical hole in the polishing block 4 and is capable of a small vertical movement therein, which is limited in an upward direction by a plate 8, attached to the block, engaging with a shoulder 9 on the boss 6. By means of the shoulder 9 andplate 8, the block 4 may be lifted clear of the glass by raising the framework of the runner. In operation, the runner framework is lowered so that when the block 4 rests on the glass, the boss 6 is clear of the plate 8 as shown in the'drawing.

The'periphery 10 of the boss 6, where, it"

contacts with the block 4, is curved, prefer- I ably to aportion of a sphere, so that it may .55 contact with the block 4 only along a line The accompanying drawing is a vertical 'by contact with the and so that the block may tilt on the 6 when required to take an even bearing onthe glass.

The line of contact between the boss 6 and the block 4 is in the horizontal plane which is indicated by the dotted line 11 and which passes through the centre of gravity of the block 4 with its felt.5; this plane is, itself, hereinafter identified by the numeral 11.-

Now, it is im ortant for effective polishing, that the polis ing blocks rotate on their axes and it is found that'they do so. rotate when they bear on the glass with a pressure which is approximately uniform over their surfaces, or when the pressure at, points more distant from the axis ofthe runner is greater than that at ints nearer to it. It appears that therotatlon is due to the ter relative velocity between glass and p0 'shing block at points more distant from the axis of the runner and'that the efiect of the greater relative velocity is annulled by I.

greater pressure at points nearer to the axis of the runner.

.Now, the centrifugal force acting'on the block, will roduce a couple tending to tilt the block, if

the plane in whichthe block is held against the centrifugal force, be above or below the centre, of gravity of the block, and this couple will cause the premure between glm and block at points more distant from the axis of therunner to be greater if the plane bev below, and less if the plane be above, the centre 'of' gravity of the block.

It is an essential feature of this invention that the plane in which the block 6 is held periphery 10 of the boss 6, be either substantiall in the lane 11 of the centre of gravity 0 the bloc or below 7 it, so that thecentrifugal force has no apreciable efiect in increasing thepressure tween glass and block at points nearer to the axis of the runner.

It is to be noted that the polishing block.

4 is driven by the best, so that the means for drivingthe block are the same as the means. for; holding it l.qzgininst centrifugal force. Thisis the prefe construction, but

the invention is not confined to the particular type of polishing block and mounting shown,

and is applicable to any block on I, rotating "runner, which is free to rotate and to tilt,

and is used-for polishing or obrading of anyhdescription.

ving describedmy invention, I declare that what I claim and desire to secure by Letters Patent is 1. Abrading apparatus of the type described, comprising abrading blocks free to rotate and tilt, characterized by an abrading block being held against'centrifugal force in a plane which is not above the centre of gravity of the block.

2. In abrading apparatus of the type described, the combination with a rotating runner framework and a stub spindle mounted thereon so as to be capable of rotation only,

of a boss attached to the end of the spindle, a polishing block upon the spindle, an opening in the block Within Which the boss is movable axially, and permitting tilting movement of the block about the boss, the periphery of the boss contacting with the block in a plane which is not above the centre of gravity of the block.

In testimony whereof I have afiixed my signature hereto.

FREDERIC BARNES WALDRON. 

